World Bank Document

NOT T1IS RUOIXT HAS TO THE BEEN RELEASED EXECUTIVE DIRECTORS RESTRICTED RETURN TO ~ CIRCULATING COPY RI EBE RETURNED To ARCHIVES REPORTS DESK Public Disclosure Authorized WITH N ONE W Eli1 r art was prepared for use within the Bank. It may not be published nor may it be quoted as representing the Bank's views. The Bank accepts no responsibility for the accuracy or completeness of the contents of the report. INTERNATIONAL. BANK FOR RECONSTRUCTION AND DEVELOPMENT Public Disclosure Authorized RIVER BASIN DEVELOPMENT CEYLON Public Disclosure Authorized May 1961 Public Disclosure Authorized Department of Technical Operations April 20, 1961 REPORT BY BANK MISSION ON RIVER BASIN DEVELOPMENT, CEYLON Terms of Reference A Bank Mission consisting of Messrs. R. A. Wheeler, Christian Finne and Albert R. Johnson visited the Island of Ceylon for about five weeks from the end of January, 1961 to the first week in March. The terms of reference for the Mission were contained in a letter from the Bank to the Ceylon Govern- ment, dated December 28, 1960. The general purpose was to make a study of river basin development covering all aspects of such development, including power, irrigation and flood control. In particular, the Mission was requested to review all studies so far made of the various river basins, to determine what further studies should be undertaken together with recommendations on how they should be 4nitiated and estimate of time required for their completion, and to sub- mit recommendations concerning priorities between projects for development of the various river basins, Reports reviewed Reports were available on multipurpose projects in the Mahaweli Ganga: and Walawe Ganga Basins and a preliminary statement was presented on the Kelani Ganga Basin. Reports on projects for the primary purpose of irrigation were available in the Aruvi Aru and Kala Oya Basins. These were reviewed by the Mission and the basins inspected. The Mission also visited the power projects in the Maskeliya Oya and Kehelgamu Oya Basins and the partially completed multipurpose development project in the Gal Oya Basin. In addition, the Mission reviewed the summary table that was prepared by the Ceylon Department of Irrigation concerning projects for irrigation in seventeen other river basins. The list of reports reviewed by the Mission is given in Appendix 1. Mahaweli Ganga Diversion Project The Mahaweli Ganga Basin has the largest watershed of the island (4034 sq. mi.), being more than three times the size of the next watershed in size (1268 sq. mi.), the Aruvi Aru Basin. The average annual discharge of the Mahaweli Ganga-is also one of the two largest, 6 million acre feet, the Kalu Ganga also being about the same volume. A preliminary report on the Mahaweli Diversion Scheme has been prepared by ICA. It deals with the feasibility of diverting a substantial portion (about 1.6 MAF) of the Mahaweli Ganga waters near Kandy and conveying -2 - the water to the North Central Province (NGP) for irrigation and genera- tion of electrical energy at favorable locations. Some flood-protection benefits will be provided in the Kandy area, and additional water will be made available for domestic uses in the cities of Kandy and Anuradhapura. However, these benefits are small compared to the others and are not in- cluded in the benefit-cost ratio. It is a large project consisting of the construction of two dams and reservoirs, a diversion dam on the Mahaweli, four major power plants having a total of 243,000 IV installed capacity, the NCP Canal 124 miles in length, the irrigation of 215,000 acres to produce two crops per year in the Anuradhapura District of the NCP, the irrigation of .10,000 acres to produce two crops per year in the Elahera-Kantalai and Angamedilla systems and the construction of three minor canal power plants in the lower reaches of the N-C-P Canal. This project will require an ultimate investment of about 1203 million rupees (US$ 250 million) in capital works, of which 613 million rupees (US$ 130 million) is foreign exchange. It is estimated that it will produce 1440 million KWH of marketable electric energy of which 1320 million XWH will be firm. The benefit-cost ratio has been estimated by ICA at 2.3 to 1. The project can be constructed in stages. The first stage would provide the benefits of irrigation for 80,000 acres, of flood control and of 90,000 KW of firm power, estimated to cost a total of 421.5 million rupees (US$ 88 million) of which 186.4 million rupees (US$ 39 million) is foreign exchange. A more detailed description is given in Appendix No. 2. This preliminary report on the feasibility of the diversion scheme was prepared by competent and experienced engineers of the ICA. They received the cooperation and assistance of Ceylonese engineers from the irrigation and electrical departments. The report is satisfactorily presented in sufficient detail to show that favorable results can be ex- pected, that the hydroelectric potential is substantial and can be developed in stages progressively with the demand and at reasonable cost and that a substantial part of the area to be irrigated is developed and needs primarily supplemental water supplies. Land classification of reconnaissance type has already been made of the lands to be irrigated. The farmers in the North Central Province have had considerable experience with irrigation so that increased food production from irrigation is likely to be both greater and more certain than from completely new irrigation areas. Assured water for irrigation in the NCP will make possible substantial gains from early adoption of improved techniques in rice production on existing areas. Substantial areas of land suitable for new irrigation farming are available in the NOP and can be developed without interference with the early gains from providing water to the presently irrigated areas with a short water supply. - 3- These cons.derations justify the conclusion that the project is ready for the necessary further detailed engineering studies and for prepara- tion of the plans for the first stage which, it is estimated, would require about a year and a half. The necessary further engineering studies are now continuing under the supervision of the ICA and Ceylonese engineers. The plans for this project are further advanced than for any other project that was reviewed by the Mission. The effect of the proposed diversion of 2500 cusecs from the Mahaweli Ganga near Kandy upon the planning for the Mahaweli Ganga Basin below the point of diversion is being studied further by the ICA engineers and the Ceylon Irrigation Department. In the summary table prepared by the Ceylon Irrigation Department, it was stated that the diversion to the basins in NCP was economically justified because of the much greater areas of existing irrigated lands in these basins than in the lower Mahaweli Ganga Basin. Walawe Ganga Basin The Walawe Ganga, located in the Southeastern part of Ceylon, has a drainage area of 954 square miles and an average annual discharge of about 1.6 million acre feet. It is the fifth river of Ceylon in volume of discharge. A general survey of this basin was carried out by the Photographic Survey Corporation of Canada under the Colombo Plan assistance program. The report was completed in July 1960. The purpose of the survey was to provide an inventory of geology, land forms, soils, land use, forest cover and hydro- logy and to make suggestions and recommendations concerning future use of the land and water resources. The report points out the lack of hydrologic data and information on floods and recommends the installation of additional discharge and rain gauging stations. It proposes a four-stage program of development and is described in greater detail in Appendix No. 3. Stage 1 includes the construction of a storage dam on the upstream Walawe Ganga, a diversion tunnel to a forebay reservoir on the Diyawini Oya and a power plant on the north bank of the Katupal Oya at the foot of a steep escarpment. A dam constructed across the Katupal Qya would create a regula- ting reservoir for the irrigation canals. These works correspond to the Samanala Wewa project which is described in Appendix No. 4. Stage 1 would also include a diversion dam on the Walawe Ganga below its confluence with the Katupal Oya as well as the necessary irrigation canals. Stage 2 includes a storage dam on the Weli Oya, and irrigation canals; stage 3, storage dams on the right bank tributaries, Yuda Oya and have Rakwana Ganga, with irrigation canals. The flows of these tributaries not been computed and no field investigations have been made of possible dam sites. -4- Stage 4 includes a storage dam at one of four possible sites on the lower Walawe Ganga above Embilipitiya to provide balancing storage for irrigation of the coastal area. This stage can only be developed after plans for the upstream works have been completed so that the water supplies available in the lower region can be evaluated. The Uda Walawe Project which is described in Appendix No. 5, corresponds to Stage 4 and was developed before the Canadian study became available. The survey report concludes that the possible development looks sufficiently promising to justify more detailed studies which should include, in particular, the evaluation of the hydrologic information obtained from the additional gauging stations, detailed investigations of possible dam sites, topographical surveys of lands to be irrigated, land classification survey and operational studies to establish the necessary coordination of water releases for power production and irrigation. Kelani Ganga Basin The Kelani Ganga discharges into the sea at Colombo.

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